Pictures ?Redoing a well LOVED and HARD USE ZIPPO may not be wise. May not ever improve value.
The goal isn't to improve the value, but to preserve the lighter itself. With the crackle worn off, the exposed steel is starting to rust. Painting it with a durable paint that isn't the crackle would be fine, too, but if there's a way to imitate the crackle, I'd prefer that. I'll upload some photos soon.